The invention relates to the field of guides for power cutting tools, and more particularly to a clamping guide for hand power tools which has integral measuring means.
When cutting a work-piece using a power cutting tool such as a power hand saw, the carpenter typically measures a pencil line on the work-piece and guides the saw along the line by the unaided eye. To ensure that such saw cuts are straight and accurate, various guides have been developed which are secured to the work piece. For example, U.S. Pat. No. 3,287,808 Fortune issued Nov. 29, 1966 discloses a saw guide which is clamped to the workpiece and has an edge against which the saw is guided. An elongated secondary guide swings over the guide into operative position to permit a scribe which slides along the secondary guide to mark a reference line. Similarly, U.S. Pat. No. 4,522,098 Bliss, issued Jun. 11, 1985 discloses a saw guide which is clamped to the workpiece and has a rib against which the saw is guided. Similarly, U.S. Pat. No. 5,385,183 Ferranti issued Jan. 31, 1995 discloses a saw guide which grips the workpiece and has an edge against which the saw is guided. None of these guides has apparently achieved commercial success as they are awkward and inconvenient for a busy tradesperson to position on the workpiece. U.S. Pat. No. 4,494,434 Young, issued Jan. 22, 1985 discloses a saw guide which has an integral gauge for measuring the required spacing between the guide and the saw cut, but without an expansion piece, it is only suitable for short cuts on narrow workpieces and is held on the workpiece by hand.
There is therefore a need for an improved power tool guide which has an integral measuring gauge for locating the guide and an integral clamp which permits the guide to be quickly positioned and clamped on both narrow and wide workpieces.
The present invention therefore provides a power tool guide adapted for releasably securing to a workpiece having upper and lower planar surfaces, the power tool guide comprising i) a first planar plate having a planar upper surface, a planar lower surface and a first straight guide edge perpendicular to the first planar upper surface; ii) a second planar plate extending perpendicularly to the first planar surface and to the straight guide edge, the second planar plate having a planar inner surface and a planar outer surface; and iii) clamping means secured to the planar outer surface of the second planar plate, the clamping means having an adjustable lower clamping jaw adapted to bear against the lower surface of the workpiece and thereby releasably secure the guide to a workpiece. According to one aspect of the invention the power tool guide further comprises iv) a pivotable bar having a surface for receiving an off-set marking, movable along the length of the upper surface of the first planar plate in a direction parallel to the first straight guide edge, and adapted to pivot from a position extending perpendicularly to, and beyond the edge of the first straight guide edge to a position spaced from the first straight guide edge to permit the passage of the power tool.